1. Technical Field
The present invention is directed to data processing systems. More specifically, the present invention is directed to a method, apparatus, and computer program product for permitting access to a storage drive while the drive is being formatted.
2. Description of Related Art
Hard drive capacities have been doubling approximately every 18 months. As a result, the time it takes to format a hard drive has also been increasing. For example, for a SCSI disk drive that is capable of storing 300 Gbytes, it takes approximately 105 minutes to format the drive.
A disk drive is accessed using a logical block address (LBA). The drive is divided into multiple different LBAs. The smallest unit in a disk drive that can be accessed by a user application is an LBA. An LBA identifies a particular cylinder, head, and sector location within the drive.
In order to format a disk drive, a host that is coupled to the disk drive will send a FORMAT UNIT command to the disk drive. A disk drive controller, included within the disk drive, then receives this FORMAT UNIT command. The disk drive controller executes the FORMAT UNIT command by identifying bad logical block addresses (LBAs) within the drive, building a track layout table that indicates which LBAs are bad and thus are to be skipped, and writing an initialization pattern to the good LBAs in the drive. While the disk controller is in the process of formatting the drive, the host cannot access the drive to read data from or write data to the drive.
Once the disk controller has completed formatting the drive, the controller then indicates to the host that it has finished. The disk controller indicates to the host that it has finished formatting the drive by returning a COMMAND COMPLETE response to the host. Once the host receives the COMMAND COMPLETE response, the host can then begin accessing the drive to read and/or write data to the drive. Because the format operation can take a very long time, the drive is unavailable for this long period of time.
Therefore, a need exists for a method, apparatus, and computer program product for permitting access to a storage drive, such as a hard disk drive, while the drive is being formatted.